strconv: CanBackquote doesn't work with 0x7f and above

[bradfitz]

strconv.CanBackquote doesn't seem to work as advertised.

Noticed via https://golang.org/cl/76730043/

Doesn't handle bad UTF-8 either: http://play.golang.org/p/zLTuou_Tha

Fix, or document?

[rui314]

Comment 1:

It doesn't also take into account Unicode C1 control characters. Not sure it's intended
or not.

[robpike]

Comment 2:

// CanBackquote reports whether the string s can be represented
// unchanged as a single-line backquoted string without control
// characters other than space and tab.
Since U+007F is a control character, the function should protect against them. That is a
bug.
Regarding bad UTF-8, it's much less clear. Badly encoded UTF-8 is not a "control
character". On the other hand, if the UTF-8 is bad, the string cannot be "represented
unchanged" in some sense.
I will address the 7F issue and open a new issue for bad UTF-8, which is a larger topic
less clear cut. See issue #7572.

[robpike]

Comment 3:

This issue was closed by revision f34251a.

Status changed to Fixed.